Cron (crond) daemon or service is use to execute scheduled commands or scripts. Cron wakes up every minute, examining all stored crontabs, checking each command to see if it should be run in the current minute.(source)
Crontab Guru
The quick and simple editor for cron schedule expressions
Task: Start cron service
ON RHEL/Centos Linux 7.x user:
# systemctl start crond.serviceTask: Stop cron service
OR RHEL/Centos Linux 7.x user:
# systemctl stop crond.serviceTask: Restart cron service
To restart the cron service, use:
OR RHEL/Centos Linux 7.x user:
# systemctl restart crond.serviceTask: Test if cron is working
Add the following entry to your crontab. To do so, enter the command
crontab -e
And then add:
* * * * * /bin/echo "foobar" >> /your-path/your-file-name.txtAfter a minute, a file should be created under the specified path, holding the “foobar” content. If you can see the file, congrats, cron is working fine.
(source)